Comparative analysis of integrin expression on monocyte-derived macrophages and monocyte-derived dendritic cells.

Summary Both macrophages (MAC) and dendritic cells (DC) are members of the mononuclear phagocyte system (MPS) with monocytes (MO) as common precursor cells. Cells of the MPS are able to take up, process and present antigens to T lymphocytes, thereby inducing a primary or secondary immune response. Adhesion molecules are of crucial importance for the interaction of antigen-presenting cells with immune cells, especially T lymphocytes. By representational difference analysis, we identified CD49c (VLA-3), a member of the β₁-integrin family of adhesion receptors, as differentiation-associated antigen in MO-derived MAC. In contrast, MO-derived DC did not express CD49c mRNA. These data prompted us to compare the integrin expression pattern of MAC and DC. Both cell types showed a low expression of the α-chains of the β₁-integrins CD49a, CD49b, CD49d and CD49e, whereas a marked difference was observed for CD49c and CD49f. Expression of both integrins increased during MO to MAC differentiation, but was not detectable on DC. In parallel the β₁-chain (CD29) was clearly up-regulated during MO to MAC differentiation but was only weakly expressed on DC. On the other hand, the β₂-integrins CD11a, CD11b, CD11c and CD18 were all expressed on MAC and DC. Beside their role in cell–cell interaction and adhesion, β₂-integrins are also known as possible binding molecules for bacteria and lipopolysaccharide (LPS), especially for high LPS concentrations. Therefore we investigated the LPS response of MAC versus DC in terms of tumour necrosis factor-α (TNF-α) release. DC were less responsive to low doses of LPS, which can easily be explained by the very low CD14 expression on DC compared for MAC. In contrast, the TNF-α response was comparable to MAC when DC were stimulated with high LPS concentrations. Our results show a specific, differentiation-dependent pattern of... [ABSTRACT FROM AUTHOR]